Changed: Use PostCSS 6 (#9)

- Also, update jscs, jshint, and tape

Author: jonathantneal

.travis.yml

@@ -1 +1,3 @@
 language: node_js
+node_js:
+  - 4

package.json

@@ -20,13 +20,13 @@
     "index.js"
   ],
   "dependencies": {
-    "postcss": "^5.0.4"
+    "postcss": "^6.0.1"
   },
   "devDependencies": {
-    "jscs": "^2.1.0",
-    "jshint": "^2.8.0",
+    "jscs": "^3.0.7",
+    "jshint": "^2.9.4",
     "npmpub": "^3.1.0",
-    "tape": "^4.0.3"
+    "tape": "^4.6.3"
   },
   "scripts": {
     "lint": "npm run jscs && npm run jshint",